Hi. I fond 2 post in a p2p forum where spoke about that problem..
not for SFML but other case.
The story isn't clear and no solution was found.
Looking in PeerGuardian I found that the packet
is signed as outgoing packet vs 213.186.33.2: Copyright-agency.com/co-peer-right agency.
I don't know well PeerGuardian but see that slow down many sites but..
for now blocking onli SFML.
Today PeerGuardian announce me that it was auto killed ^_^ (internal problem) booo
Have a Good day.. bye-bye